NASA’s new planet finder is in space. Now what?

Most everyone reading this story will probably know that a SpaceX Falcon 9 rocket launched on Wednesday carrying a NASA spacecraft into orbit—the Transiting Exoplanet Survey Satellite—that will further the space agency’s mission of searching for exoplanets. Less well known is the TESS spacecraft’s clever orbit, which will enable an on-a-budget but robust science mission of searching for planets transiting in front of nearby stars. This “lunar resonant” orbit, which has never been used by a spacecraft, will allow TESS to both observe nearby stars and transmit data back to Earth with a minimal energy expenditure. (The useful lifetime of a spacecraft is often determined by its amount of onboard propellant). Lunar resonant orbit Science missions often need continuous and unobstructed views of their targets, and TESS is no different, as it will monitor about 200,000 relatively nearby stars for minuscule changes in their brightness. NASA’s previous planet-hunter that searched for similar transits, the Kepler mission, observed its targets from an Earth-trailing, heliocentric orbit about 10 million km from our planet. Such an orbit has high costs in terms of energy needed to reach it, station keeping, and data limitations. For TESS, the lunar resonant orbit will bring it to within as close as 108,000 km of Earth’s surface (or about three times the height of geostationary orbit) and as far out as 373,000km away from the Earth, which is just inside the Moon’s orbit. During a three-hour period at its closest approach, TESS will orient itself to send robust… [Read full story]